The effect of obliquity-driven changes on paleoclimate sensitivity during the late Pleistocene


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Peter.Koehler [ at ] awi.de

Abstract

Some studies suggest that specific equilibrium climate sensitivity S might be state-dependent. Reanalyzing existing paleodata of global mean surface temperature ∆Tg and radiative forcing ∆R of CO2 and land ice albedo for the last 800,000 years we show that this state-dependency of S is only found if ∆Tg is based on reconstructions, and not when ∆Tg is based on model simulations. Furthermore, during times of decreasing obliquity (periods of land-ice sheet growth and sea level fall) the multi-millennial component of reconstructed ∆Tg is diverging from atmospheric CO2, while in simulations both variables vary more synchronously. For a reconstruction-based extrapolation of S to the future we eliminate these periods due to an expected sea level rise. Consequently, S determined from proxy-based reconstructions without these data with strong ∆Tg-CO2 divergence is less state-dependent or even constant (state-independent), and yields into an equilibrium warming for 2 × CO2 of 1.9–3.8 K.



Item Type
Conference (Talk)
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Not peer-reviewed
Publication Status
Published
Event Details
PALMOD International Open Science Conference, 07 Apr 2018 - 08 Apr 2018, Vienna, Austria.
Eprint ID
46969
Cite as
Köhler, P. , Knorr, G. , Stap, L. , Ganopolski, A. , de Boer, B. , van de Wal, R. S. W. , Barker, S. and Rüpke, L. H. (2018): The effect of obliquity-driven changes on paleoclimate sensitivity during the late Pleistocene , PALMOD International Open Science Conference, Vienna, Austria, 7 April 2018 - 8 April 2018 .


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